AQA GCSE Combined Science: Trilogy Biology Paper 1 (Higher), 2020: Question 2

14 marks · Standard Demand difficulty · Short Answer

Answer a series of questions about digestion and absorption in the small intestine, including enzymes, villi adaptations, transport processes, and a magnification calculation.

Practise this question

Question

The question page contains nine linked biology parts about digestion and absorption. It asks for the enzyme that digests starch, the organ where most food molecules are absorbed, an advantage of an electron microscope over a light microscope, identification of a blood vessel labelled X on a villus diagram, a magnification calculation using magnification equals size of image divided by size of real object, the names of the processes by which sugar enters two cells, one use of sugar in the body, and a 4-mark explanation of how villi are adapted for efficient absorption. The page includes a diagram of two villi with an enlarged circular inset showing one surface cell labelled microvilli and mitochondria, and a second diagram showing two surface cells, A and B, with dots representing sugar molecules inside and outside the cells.
Question text

02 Starch is digested to form sugar molecules in the digestive system.

02.1 What is the name of the enzyme that digests starch?

[1 mark]

02.2 Where are most food molecules absorbed?

[1 mark]

Tick ( ) one box.

Large intestine

Liver

Small intestine

Stomach 8

Figure 2 shows two villi.

Figure 2 also shows one cell on the surface of a villus as seen using an

electron microscope.

Figure 2

02.3 Give one advantage of using an electron microscope compared with using a

light microscope.

[1 mark]

02.4 What type of blood vessel is labelled X?

[1 mark]

Tick ( ) one box.

Artery

Capillary

*08* Vein

02.5 The real length of one villus is 0.8 mm

Calculate the image length if the villus is viewed at a magnification of ×20

Use the equation:

size of image

magnification =

size of real object

[3 marks]

Image length = mm

Figure 3 shows two cells from the surface of a villus.

There are sugar molecules inside and next to each cell.

Figure 3

02.6 Name the process by which sugar moves into cell A.

[1 mark]

02.7 Name the process by which sugar moves into cell B.

[1 mark]

02.8 Give one use of sugar in the body.

[1 mark]

02.9 Figure 2 is repeated below.

Figure 2

Explain how villi are adapted for efficient absorption of sugar molecules.

[4 marks]

Mark scheme

Show the mark scheme The mark scheme is a table listing answers for questions 02.1 to 02.9 with marks and specification references. Accepted answers include amylase, small intestine, greater magnification or higher resolving power for electron microscopes, capillary, image length equals 16 mm from 20 equals image length over 0.8, diffusion, active transport, and uses of sugar such as respiration, glycogen formation, or making amino acids or proteins. The final 4-mark level-of-response answer credits links between villus structure and function, including many microvilli for large surface area, thin walls and nearby capillaries for a short diffusion pathway, good blood supply to maintain a diffusion gradient, and many mitochondria providing energy for active transport.

AO /

Question Answers Extra information Mark

Spec. Ref.

02.1 allow phonetic spelling AO1

amylase allow carbohydrase 1 4.2.2.1

do not accept amylose

02.2 small intestine 1 AO1

4.2.1

4.2.2.1

02.3 any one from: 1 AO1

• greater magnification allow can see (smaller) sub- 4.1.1.5

• higher resolving power cellular structures / parts

allow can see more detail

(inside cells)

allow reference to 3-D images

02.4 capillary 1 AO2

4.2.2.1

4.2.2.2

02.5 image length 1 AO2

20 =

0.8 4.1.1.5

RPA 1

image length = 0.8 x 20 1

image length = 16 (mm) 1

02.6 diffusion 1 AO3

4.1.3.1

02.7 active transport allow active uptake 1 AO3

4.1.3.3

AO /

Spec. Ref.

02.8 any one from: 1 AO1

• respiration allow as an energy source 4.4.2.1

do not accept to make / use / 4.4.2.3

create / produce energy

• to form glycogen

• to make amino acids / allow to make lipid / fat

proteins

02.9 Level 2: Relevant points (reasons/causes) are identified, given in 3–4 AO2

detail and logically linked to form a clear account. 4.1.1.3

4.1.3.1

Level 1: Points are identified and stated simply, but their relevance 1–2 4.1.3.3

is not clear and there is no attempt at logical linking. 4.2.2.1

No relevant content 0

Indicative content

• have (many) microvilli

• (to) increase surface area

• wall of villus only one cell thick or is thin

• capillaries are close to surface

• (so) short pathway

• good blood supply

• (to) transport food molecules away or to the body

• (and) maintain a diffusion gradient

• cells have many mitochondria

• (where) respiration takes place

• (where) energy is transferred

• (as) active transport requires energy

• energy is needed to absorb sugar / food / molecules

For Level 2 must make links between structure and it’s function

Total 14

How to answer it

Villi, enzymes and sugar absorption

What this question tests

Knowing the enzyme for starch digestion, where food is absorbed, how microscope choice affects detail, identifying blood vessels in a villus, using magnification correctly, and explaining how villi are adapted for absorption. Marks mainly reward correct recall and clear links between structure and function.

Question 02.1 – Name the enzyme that digests starch

✅ Correct answer

Amylase

1 mark for the correct enzyme name.

💡 Key knowledge

  • Amylase breaks down starch into sugars.
  • It is found in the mouth, pancreas and small intestine.

❌ Common errors

  • Amylose is wrong — that is not an enzyme.
  • Don’t just say “enzyme” — you need the name.

Question 02.2 – Where are most food molecules absorbed?

✅ Correct answer

Small intestine

1 mark for the correct location.

💡 Key knowledge

  • Most digested food is absorbed in the small intestine through villi.
  • The villi provide a large surface area for absorption.

🧠 Exam technique

This is a straight recall question. Tick one box only.

Question 02.3 – Advantage of using an electron microscope

✅ Correct answer

Any one of:

  • Greater magnification
  • Higher resolving power
  • Can see more detail / smaller sub-cellular structures

1 mark for one valid advantage.

💡 Key knowledge

Electron microscopes show much more detail than light microscopes, so you can see organelles and tiny cell structures clearly.

❌ Common errors

  • “It is bigger” is not enough unless you say greater magnification.
  • “It is better” is too vague.

Question 02.4 – What type of blood vessel is X?

✅ Correct answer

Capillary

1 mark for the correct vessel.

💡 Key knowledge

  • Capillaries surround villi and are the site of exchange with absorbed nutrients.
  • They have very thin walls, helping diffusion.

🧠 Exam technique

In villus diagrams, the tiny vessel near the surface is usually a capillary, not a vein or artery.

Question 02.5 – Magnification calculation

📐 Calculations: step-by-step

  1. Use the equation: magnification = size of image ÷ size of real object
  2. Rearrange to find image size: size of image = magnification × real size
  3. Substitute the values: image length = 20 × 0.8
  4. Work out the answer: image length = 16 mm

Final answer: 16 mm

3 marks: 1 for the rearranged equation, 1 for substitution, 1 for the correct answer.

🧠 Exam technique

  • Always keep units consistent.
  • If the answer is in mm, don’t change it unless told to.
  • Show the equation clearly so you can gain method marks.

❌ Common errors

  • Using 0.8 × 20 = 16 but forgetting the unit.
  • Dividing instead of multiplying.
  • Writing cm when the question asks for mm.

Question 02.6 – How do sugar molecules move into cell A?

✅ Correct answer

Diffusion

1 mark for the correct process.

💡 Key knowledge

  • Diffusion is the net movement of particles from a high concentration to a low concentration.
  • It is a passive process, so no energy is needed.

❌ Common errors

  • Do not say osmosis — sugar is not water.
  • Do not say active transport for cell A in this diagram.

Question 02.7 – How do sugar molecules move into cell B?

✅ Correct answer

Active transport

1 mark for the correct process.

💡 Key knowledge

  • Active transport moves substances from low concentration to high concentration.
  • It needs energy from respiration.

🧠 Exam technique

Look at the concentration of sugar molecules outside and inside the cell. If sugar is being moved into a region with more sugar, diffusion cannot explain it.

Question 02.8 – One use of sugar in the body

✅ Correct answers

Any one from:

  • Respiration
  • To form glycogen
  • To make amino acids / proteins
  • To make lipids / fats

1 mark for one valid use.

💡 Key knowledge

  • Glucose is used in respiration to release energy.
  • Excess glucose can be stored as glycogen in the liver and muscles.

❌ Common errors

  • “Make energy” is not accepted — glucose is used for respiration to release energy.
  • “Produce energy” is too vague.

Question 02.9 – Explain how villi are adapted for efficient absorption of sugar molecules

4 marks: you need linked explanations, not just a list

✅ Full-mark points

  • Villi have many microvilli, which increase surface area.
  • The villus wall is one cell thick, so the diffusion pathway is short.
  • There is a good blood supply / many capillaries close to the surface, which carries sugars away and maintains a diffusion gradient.
  • Cells have many mitochondria for respiration, providing energy for active transport.

Top responses link structure to function: “because”, “so”, “this means”.

🧠 Exam technique

  • To reach Level 2, make clear links between structure and function.
  • Use connected statements, not separate facts.
  • Example chain: many microvilli → larger surface area → more sugar absorbed.

❌ Common errors

  • Just naming features without explaining them loses marks.
  • “Mitochondria are for energy” is incomplete unless you say energy is needed for active transport.
  • Do not forget the role of capillaries in removing sugar and maintaining the gradient.

💡 Example 4-mark answer

Villi have many microvilli to increase surface area, so more sugar can be absorbed. Their walls are one cell thick, giving a short diffusion distance. They have a good blood supply with capillaries close to the surface, which carries sugar away and maintains a concentration gradient. The cells also contain many mitochondria, which release energy for active transport.

📐 How examiner marks this kind of answer

  • 1 mark for a correct point.
  • More marks for explaining why that feature helps absorption.
  • Best answers cover surface area, diffusion distance, blood supply and energy for active transport.

Topics

Biology · Required Practicals · B1: Cell Biology · B2: Organisation · B4: Bioenergetics · Biology Required Practicals

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Biology Paper 1 (Higher), 2020. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.